These studies are designed to elucidate how and why parenteral drug abusers become infected. We will continue studying how to diagnose and treat serious infections with Staphylococcus aureus in drug users, using a counterimmunoelectrophoretic method of demonstrating antibodies to staphylococccal teichoic acids. Specific types of immunoglobulins involved in this response will be identified. Studies of how best to treat infections with staphylococci, pseudomonas and serratia will be initiated. The specific effect of methadone on antibacterial systems in vitro and on experimental bacterial infections in mice will be carried out. BIBLIOGRAPHIC REFERENCES: Sheagren JN, Tuazon CU, Griffin, C, Padmore N: Rheumatoid factor in acute bacterial endocarditis. Arth. Rheum. 19:887-890, 1976. Lin MYC, Tuazon CU, Sheagren JN: Synergism of aminoglycosides and carbenicillin against antibiotic resistant strains of Serratia marcescens. Am. Soc. Microbiol. Progr. #135-C, 180, 1977.